The present invention relates to tags and, more specifically, to tags with tunable retro-reflectors that support data readout.
Sensor nodes or tags on the edge of a given network need to have a low power operational mode in order to maintain operational conditions and to avoid having to be supplied with a constant supply of high power. For example, while a wireless data uplink condition between the sensor nodes or tags and a central host element where signals are actively transmitted is often one of the most power hungry functions of the given network, a low-power solution involves the use of a reader to detect changes of capacitance or inductance on tags by way of radio frequency (RF) signals and an RF antenna.
Problems with using RF signals and RF antennas also exist, however, because a footprint of a given tag might be too small to accommodate efficient antenna operation without increasing operating frequencies to tens of GHz. Additional problems relate to RF antennas having relatively low signal-to-noise ratios. That is, while a mirror can be used on a chip to reflect light towards the reader (therefore sending a ‘1’) or away from the reader (therefore sending a ‘0’), when the mirror is very small (i.e., on the order of <50 um in each dimension), laser light reflected from the background can overwhelm a signal at the reader.